Vehicle lighting control system with fog detection

ABSTRACT

A fog detecting system for a vehicle includes a camera disposed at a vehicle and having a field of view forward of the vehicle, and a non-imaging sensor disposed at the vehicle and having a field of sensing forward of the vehicle. The camera captures image data and the non-imaging sensor captures sensor data. A control includes at least one data processor operable to process image data captured by the camera and sensor data captured by the non-imaging sensor. The control, responsive to processing of image data captured by the camera and processing of sensor data captured by the non-imaging sensor, determines presence of fog ahead of the vehicle and in the field of view of the camera and in the field of sensing of the non-imaging sensor.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the filing benefits of U.S. provisionalapplication Ser. No. 62/561,702, filed Sep. 22, 2017, which is herebyincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to a vehicle vision system for avehicle and, more particularly, to a vehicle vision system that utilizesone or more cameras at a vehicle.

BACKGROUND OF THE INVENTION

Use of imaging sensors in vehicle imaging systems is common and known.Examples of such known systems are described in U.S. Pat. Nos.5,949,331; 5,670,935 and/or 5,550,677, which are hereby incorporatedherein by reference in their entireties.

Lighting control systems are currently made in a way to detect the lightbrightness outside of a vehicle for turning the rear and head lights(beside possible daytime running lights, which may be always on) on whenit is getting dark. Typical solutions have light sensitive sensors orcameras. Rain sensors are known for detecting rain or hail. Some systemsmay automatically turn on the vehicle lights upon a defined rain or hailintensity. Typically these turn on the windshield wipers.

SUMMARY OF THE INVENTION

The present invention provides a driver assistance system for a vehiclethat utilizes one or more cameras to capture image data representativeof images exterior of the vehicle, and one or more non-imaging sensorsto capture sensor data. The present invention provides a fog detectingsystem that includes a control comprising at least one processoroperable to process image data captured by the camera and sensor datacaptured by the non-imaging sensor. The control, responsive toprocessing of image data captured by the camera and processing of sensordata captured by the non-imaging sensor, is operable to detect fog aheadof the vehicle. The determination of fog (or other reduced visibilitycondition) may be achieved by comparing signals or outputs derived fromprocessing of captured image data with signals or outputs derived fromprocessing of captured sensor data.

For example, the system may detect an object approaching the vehicle(such as ahead of the vehicle and at or in or near the path of travel ofthe vehicle) via a non-imaging sensor (such as a RADAR sensor or thelike), and the system may also utilize an imaging sensor or camera tocapture image data of the area ahead of the vehicle to detect objects orvehicles ahead of the equipped vehicle. The distance at which the objector vehicle is first detected by the camera (such as by processing ofimage data captured by the camera) as the object and vehicle approachone another is dependent on the visibility ahead of the vehicle and thusis adversely affected if fog is present ahead of the vehicle.

Thus, when the camera first detects a vehicle that is closer to theequipped vehicle than a threshold distance (such as a distance selectedbased on the resolution of the camera and/or lens of the camera, such asa distance at which the camera can detect objects under normal (e.g.,daytime, with no fog, rain, dust) visibility conditions), the systemdetermines that there is fog (or other visibility hindering condition)ahead of the vehicle. The system may adjust a lighting system of thevehicle or a driving or cruise control system of the vehicle responsiveto determination that fog (or other reduced visibility condition) ispresent forward of the vehicle.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vehicle with a fog detecting systemthat incorporates cameras and non-imaging sensors in accordance with thepresent invention;

FIG. 2 is a plan view of the vehicle of FIG. 1; and

FIG. 3 is a block diagram of the fog detecting system of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vehicle vision system and/or driver assist system and/or objectdetection system and/or alert system operates to capture images exteriorof the vehicle and may process the captured image data to display imagesand to detect objects at or near the vehicle and in the predicted pathof the vehicle, such as to assist a driver of the vehicle in maneuveringthe vehicle in a rearward direction. The vision system includes an imageprocessor or image processing system that is operable to receive imagedata from one or more cameras and provide an output to a display devicefor displaying images representative of the captured image data.Optionally, the vision system may provide a display, such as a rearviewdisplay or a top down or bird's eye or surround view display or thelike.

Referring now to the drawings and the illustrative embodiments depictedtherein, a sensing system for a vehicle 12 includes at least oneexterior viewing imaging sensor or camera 10, such as a forward viewingimaging sensor or camera, which may be disposed at and behind thewindshield 14 of the vehicle and viewing forward through the windshieldso as to capture image data representative of the scene occurringforward of the vehicle (FIG. 1). Optionally, the system may includemultiple exterior viewing imaging sensors or cameras, such as a forwardviewing camera at the front of the vehicle, and a sideward/rearwardviewing camera at respective sides of the vehicle, and a rearwardviewing camera at the rear of the vehicle, which capture images exteriorof the vehicle. The camera or cameras each include a lens for focusingimages at or onto an imaging array or imaging plane or imager of thecamera. Optionally, the forward viewing camera may be disposed at thewindshield of the vehicle and view through the windshield and forward ofthe vehicle, such as for a machine vision system (such as for trafficsign recognition, headlamp control, pedestrian detection, collisionavoidance, lane marker detection and/or the like). The system of thepresent invention also utilizes a radar or lidar sensing system 16,which has a forward sensing sensor 18 (or plurality of sensors) disposedat a forward portion of the vehicle and sensing forward of the vehiclein the direction of travel of the vehicle. The forward field of view ofthe forward viewing camera at least in part encompasses or overlaps theforward field of sensing of the forward sensing sensor. Also, theforward range of sensing by the forward sensing non-imaging sensor isgreater than a forward range of imaging by the forward viewing camera.The system includes a control or electronic control unit (ECU) orprocessor that is operable to process image data captured by the cameraor cameras and may detect objects or the like and/or provide displayedimages at a display device for viewing by the driver of the vehicle. Thedata transfer or signal communication from the camera to the ECU maycomprise any suitable data or communication link, such as a vehiclenetwork bus or the like of the equipped vehicle.

Current light control systems are unable to detect dust, fog (or clouds)or reduced visibility such as due to snowfall. Approaches are known atwhich the fog level gets determined by frequency filtering (La Place).That approach does not deliver reliable results since a road scene'sinherent frequency spectrum is strongly dependent on the scene'scontent, which is heavily changing while a vehicle is moving.

The system of the present invention provides for detection of dust, fog(or clouds or water vapor), reduced visibility by snowfall or otherwisereduced visibility by any other particles such as raindrops, hail, spraypollen or swarms of insects.

Many vehicles include imaging or optical detection systems including,for example, one or more forward directed cameras, stereo cameras, nearinfrared and/or far infrared cameras. Vehicles may also includenon-optical or non-imaging systems, such as ultrasonic sensors, nearinfrared based Lidar sensors (flash or scanning) and/or Radar sensors. Aproperty of the RADAR sensors is that there is little signal attenuationdue to the influence of fog (or water vapor). The LIDAR's infrared LASERfrequency is often already selected in a way to minimize attenuation byhumid air, and by that the LIDAR sensors penetrate fog, but the signalgets attenuated, and therefore the LIDAR's range gets limited by fog.Visual (RGB) mono and stereo camera vision is diminished by fogcomparable to the congestion of the human eye, since visible light getsscattered on the fog drops. Generally, the signal of shapes becomes lesssharp and the contrast decreases as the fog gets stronger or more dense.

As shown in FIG. 2, the vehicle equipped with the fog determining systemof the present invention includes an imaging or optical detection system20 including, for example, one or more forward directed cameras, stereocameras, near infrared and/or far infrared cameras, and a non-optical ornon-imaging system 22, such as RADAR and/or LIDAR and/or the like.Either by using structure from motion or other depth determinationmethods from a mono camera or by using a stereo camera, the RGB cameraimage processing may produce a depth map based on or derived from imagedata captured by these cameras. By comparing the image depth map with adepth map from LIDAR or RADAR or both, the current (RGB camera)visibility can be determined without the need of running sophisticatedfilters. Optionally, when present, an infrared camera's captured imagedata may also find use in the comparison. There may be a score which ishigher the more feature points of the LIDAR or RADAR match with thefeature points of the RGB depth map. A lower score may indicate thatthere is denser fog present. As an alternative solution, a borderline orborderline interval or threshold may be detectable from which depths thefeature points of the LIDAR or RADAR do not match with the featurepoints of the RGB depth map. That borderline or threshold may be thevisibility borderline.

As an optional addition or alternative, fog may be determined byclassifying the area in the camera's view near the head lights. Sincethe fog strongly reflects the light coming from the headlights, there isalways a bright halo around the head lights when it is foggy. Denser fogincreases the intensity of the halo. A classification algorithm mayclassify the image of that area producing a measure for the fog density.

As shown in FIG. 3, the system may include both a non-optical sensor 30and an optical sensor 32. When the optical sensor 32 detects an object,the non-optical sensor 30 determines a distance to the same object. Ifthe determined distance is at or below a threshold distance (at the timethe object is initially detected via processing of image data capturedby the optical sensor or camera as the object and equipped vehicleapproach one another), the system responds, for example, by switching onadditional lighting (e.g., head lights or fog lights) and/or alertingthe driver. Optionally, the system may reduce speed and/or enable aspeed limiter or other defensive driving techniques.

Because the distance at which the optical sensor 32 initially detectsthe object (as the object approaches or gets closer to the vehicle) isdependent upon fog intensity (or other visibility reducing condition,such as rain or snow or dust or the like) and because the distancedetermination capabilities of the non-optical sensor 30 aresubstantially unaffected by fog intensity, the system determines a levelor degree of fog intensity based on the distance at which the opticalsensor 32 initially detects the approaching object. Optionally, thenon-optical sensor 30 may determine that the distance to an objectsatisfies a threshold (i.e., is at or below a threshold distanceindicative of the presence of fog) before the object is detected by theoptical sensor 32, and thus may enable the fog lights (or otherappropriate action) without optical sensor 32 detection of the object.The non-optical sensor 30 may continually or periodically determine thedistance to the detected object or may determine distance to the objectonly upon detection of the object by the optical sensor 32.

For example, the viewing range of a forward facing camera during daytimeor nighttime conditions can be 150 meters or more, depending on theoptics, width of field of view, and imager pixel count or resolutionused. Such camera configurations effectively form a distance resolutionfor a forward facing camera as installed on a vehicle. When fog ispresent, the distance resolution (i.e., how far forward of the vehiclethe camera can first distinguish presence of an object ahead of thevehicle) decreases. Thus, if the distance resolution at which a camerafirst registers or determines presence of an object ahead of the vehicleis less than the distance resolution normally achieved by the cameraduring normal non-foggy driving conditions, the presence of fog can beinferred (due to the current distance resolution being less than athreshold distance normal for that camera in non-foggy conditions). Forexample, a given camera, during non-foggy driving conditions, can have adistance resolution of farthest-away object detection of about 150meters or more. However, in foggy conditions, this first objectdetection distance can drop to 50 meters or less. Thus, a thresholddistance used in the system of the present invention may be 50 meters or75 meters (or more or less), and the threshold distance may be selectedbased on the camera optics, pixel resolution, and/or field of view(narrow versus wide) or the like.

Vehicle applications such as, for example, automated speed control(advanced adaptive cruise control or ACC) or speed warning functions mayuse the fog density information for adapting the vehicle speed properlyor for a warning when driving faster than the visibility distance allowsfor safe driving. Automated vehicle light controls may switch on thedriving lights responsive to a threshold determined fog density and mayturn on the fog lights responsive to a second threshold indicative ofdenser fog conditions (or rain, snowfall or other visibility diminishingweather conditions).

The more dense the degree of fog present ahead of the vehicle is, thecloser to the vehicle the object is when it is first detected ordistinguished or determined by the camera (via processing of image datacaptured by the camera). Thus, the distance ahead of the vehicle atwhich the object is detected is indicative of the degree of fog presentduring that driving event. If the degree of fog is sufficiently high orgreater than a threshold degree of fog, with such degree of fogindicated by the closeness to the vehicle when the object is firstdetected, the fog lights of the vehicle may be automatically activated.For example, if the distance is 25 meters or less, a higher degree offog may be inferred, and the fog lights may be activated to enhancevisibility in the foggy driving conditions.

Optionally, fog lights may be activated (or speed reduced, etc.) beforethe camera determines or distinguishes the object. For example, if theobject is determined (via processing of sensor data captured by thenon-imaging sensor) to be 25 meters away, but the camera has yet todetermine the presence of the object, the presence of fog or othervisibility reducing conditions may be inferred and the system canundertake appropriate action (e.g., alerting the driver and/or adjustingadaptive cruise control and/or activating the fog lights).

The camera or sensor may comprise any suitable camera or sensor.Optionally, the camera may comprise a “smart camera” that includes theimaging sensor array and associated circuitry and image processingcircuitry and electrical connectors and the like as part of a cameramodule, such as by utilizing aspects of the vision systems described inInternational Publication Nos. WO 2013/081984 and/or WO 2013/081985,which are hereby incorporated herein by reference in their entireties.

The system includes an image processor operable to process image datacaptured by the camera or cameras, such as for detecting objects orother vehicles or pedestrians or the like in the field of view of one ormore of the cameras. For example, the image processor may comprise animage processing chip selected from the EYEQ family of image processingchips available from MOBILEYE Vision Technologies Ltd. of Jerusalem,Israel, and may include object detection software (such as the typesdescribed in U.S. Pat. Nos. 7,855,755; 7,720,580 and/or 7,038,577, whichare hereby incorporated herein by reference in their entireties), andmay analyze image data to detect vehicles and/or other objects.Responsive to such image processing, and when an object or other vehicleis detected, the system may generate an alert to the driver of thevehicle and/or may generate an overlay at the displayed image tohighlight or enhance display of the detected object or vehicle, in orderto enhance the driver's awareness of the detected object or vehicle orhazardous condition during a driving maneuver of the equipped vehicle.

The vehicle may include any type of sensor or sensors, such as imagingsensors or radar sensors or lidar sensors or ladar sensors or ultrasonicsensors or the like. The imaging sensor or camera may capture image datafor image processing and may comprise any suitable camera or sensingdevice, such as, for example, a two dimensional array of a plurality ofphotosensor elements arranged in at least 640 columns and 480 rows (atleast a 640×480 imaging array, such as a megapixel imaging array or thelike), with a respective lens focusing images onto respective portionsof the array. The photosensor array may comprise a plurality ofphotosensor elements arranged in a photosensor array having rows andcolumns. Preferably, the imaging array has at least 300,000 photosensorelements or pixels, more preferably at least 500,000 photosensorelements or pixels and more preferably at least 1 million photosensorelements or pixels. The imaging array may capture color image data, suchas via spectral filtering at the array, such as via an RGB (red, greenand blue) filter or via a red/red complement filter or such as via anRCC (red, clear, clear) filter or the like. The logic and controlcircuit of the imaging sensor may function in any known manner, and theimage processing and algorithmic processing may comprise any suitablemeans for processing the images and/or image data.

For example, the vision system and/or processing and/or camera and/orcircuitry may utilize aspects described in U.S. Pat. Nos. 9,233,641;9,146,898; 9,174,574; 9,090,234; 9,077,098; 8,818,042; 8,886,401;9,077,962; 9,068,390; 9,140,789; 9,092,986; 9,205,776; 8,917,169;8,694,224; 7,005,974; 5,760,962; 5,877,897; 5,796,094; 5,949,331;6,222,447; 6,302,545; 6,396,397; 6,498,620; 6,523,964; 6,611,202;6,201,642; 6,690,268; 6,717,610; 6,757,109; 6,802,617; 6,806,452;6,822,563; 6,891,563; 6,946,978; 7,859,565; 5,550,677; 5,670,935;6,636,258; 7,145,519; 7,161,616; 7,230,640; 7,248,283; 7,295,229;7,301,466; 7,592,928; 7,881,496; 7,720,580; 7,038,577; 6,882,287;5,929,786 and/or 5,786,772, and/or U.S. Publication Nos.US-2014-0340510; US-2014-0313339; US-2014-0347486; US-2014-0320658;US-2014-0336876; US-2014-0307095; US-2014-0327774; US-2014-0327772;US-2014-0320636; US-2014-0293057; US-2014-0309884; US-2014-0226012;US-2014-0293042; US-2014-0218535; US-2014-0218535; US-2014-0247354;US-2014-0247355; US-2014-0247352; US-2014-0232869; US-2014-0211009;US-2014-0160276; US-2014-0168437; US-2014-0168415; US-2014-0160291;US-2014-0152825; US-2014-0139676; US-2014-0138140; US-2014-0104426;US-2014-0098229; US-2014-0085472; US-2014-0067206; US-2014-0049646;US-2014-0052340; US-2014-0025240; US-2014-0028852; US-2014-005907;US-2013-0314503; US-2013-0298866; US-2013-0222593; US-2013-0300869;US-2013-0278769; US-2013-0258077; US-2013-0258077; US-2013-0242099;US-2013-0215271; US-2013-0141578 and/or US-2013-0002873, which are allhereby incorporated herein by reference in their entireties. The systemmay communicate with other communication systems via any suitable means,such as by utilizing aspects of the systems described in InternationalPublication Nos. WO 2010/144900; WO 2013/043661 and/or WO 2013/081985,and/or U.S. Pat. No. 9,126,525, which are hereby incorporated herein byreference in their entireties.

Optionally, the camera may comprise a forward viewing camera, such asdisposed at a windshield electronics module (WEM) or the like. Theforward viewing camera may utilize aspects of the systems described inU.S. Pat. Nos. 8,256,821; 7,480,149; 6,824,281 and/or 6,690,268, and/orU.S. Publication Nos. US-2015-0327398; US-2015-0015713; US-2014-0160284;US-2014-0226012 and/or US-2009-0295181, which are all herebyincorporated herein by reference in their entireties.

The system may utilize sensors, such as radar or lidar sensors or thelike. The sensing system may utilize aspects of the systems described inU.S. Pat. Nos. 9,753,121; 9,689,967; 9,599,702; 9,575,160; 9,146,898;9,036,026; 8,027,029; 8,013,780; 6,825,455; 7,053,357; 7,408,627;7,405,812; 7,379,163; 7,379,100; 7,375,803; 7,352,454; 7,340,077;7,321,111; 7,310,431; 7,283,213; 7,212,663; 7,203,356; 7,176,438;7,157,685; 6,919,549; 6,906,793; 6,876,775; 6,710,770; 6,690,354;6,678,039; 6,674,895 and/or 6,587,186, and/or International PublicationNos. WO 2018/007995 and/or WO 2011/090484, and/or U.S. Publication Nos.US-2018-0231635; US-2018-0045812; US-2018-0015875; US-2017-0356994;US-2017-0315231; US-2017-0276788; US-2017-0254873; US-2017-0222311and/or US-2010-0245066, which are hereby incorporated herein byreference in their entireties.

Changes and modifications in the specifically described embodiments canbe carried out without departing from the principles of the invention,which is intended to be limited only by the scope of the appendedclaims, as interpreted according to the principles of patent lawincluding the doctrine of equivalents.

The invention claimed is:
 1. A fog detecting system for a vehicle, saidfog detecting system comprising: a camera disposed at the vehicle andhaving a field of view forward of the vehicle, said camera capturingimage data as the vehicle travels along a road; a non-imaging sensordisposed at the vehicle and having a field of sensing forward of thevehicle, said non-imaging sensor capturing sensor data as the vehicletravels along the road; a control comprising at least one data processoroperable to process image data captured by said camera and to processsensor data captured by said non-imaging sensor; wherein said controldetermines presence of an object forward of the vehicle present in thefield of sensing of said non-imaging sensor based on processing at saidat least one data processor of sensor data captured by said non-imagingsensor; wherein said control is operable to determine distance to thedetected object via processing at said at least one data processor ofsensor data captured by said non-imaging sensor as the vehicle movesalong the road; wherein said control determines a first distance to thedetected object when said control first determines presence of theobject in the field of sensing of said non-imaging sensor based onprocessing at said at least one data processor of sensor data capturedby said non-imaging sensor; wherein, as the vehicle moves further alongthe road after determining the first distance to the detected object,said control determines presence of the object forward of the vehicle inthe field of view of said camera based on processing at said at leastone data processor of image data captured by said camera; wherein saidcontrol determines a second distance to the detected object when saidcontrol first determines presence of the object within the field of viewof said camera based on processing at said at least one data processorof image data captured by said camera; and wherein said controldetermines presence of fog ahead of the vehicle responsive to differencebetween the determined second distance and the determined first distancebeing at or above a threshold amount.
 2. The fog detecting system ofclaim 1, wherein said non-imaging sensor comprises a LIDAR sensor. 3.The fog detecting system of claim 1, wherein said non-imaging sensorcomprises a RADAR sensor.
 4. The fog detecting system of claim 1,wherein said control, responsive to determination that fog is presentahead of the vehicle, adjusts a lighting system of the vehicle.
 5. Thefog detecting system of claim 4, wherein said control, responsive todetermination that fog is present that is greater than a thresholddegree of fog, actuates fog lights of the vehicle.
 6. The fog detectingsystem of claim 1, wherein said control, responsive to detection of fogahead of the vehicle, adjusts an adaptive cruise control system of thevehicle.
 7. The fog detecting system of claim 1, wherein said control,responsive to detection of fog ahead of the vehicle, generates an alertto a driver of the vehicle.
 8. The fog detecting system of claim 1,wherein said control, responsive to processing at said at least one dataprocessor of image data capture by said camera, detects a headlighthalo, and wherein said control, responsive to processing of image datacaptured by said camera, determines an intensity of the detectedheadlight halo, and wherein said control, responsive to the determinedheadlight halo intensity, determines a fog density of the detected fog.9. The fog detecting system of claim 1, wherein said control, responsiveto processing at said at least one data processor of image data capturedby said camera, produces a camera depth map, and wherein said controlcompares the camera depth map with a depth map derived from sensor datacaptured by said non-imaging sensor to determine presence of fog aheadof the vehicle, and wherein said control determines a score indicativeof matching feature points determined from the comparison, and whereinsaid control determines that fog is present ahead of the vehicle whenthe determined score is below a threshold score.
 10. A fog detectingsystem for a vehicle, said fog detecting system comprising: a cameradisposed at the vehicle and having a field of view forward of thevehicle, said camera capturing image data as the vehicle travels along aroad; a non-imaging sensor disposed at the vehicle and having a field ofsensing forward of the vehicle, said non-imaging sensor capturing sensordata as the vehicle travels along the road; a control comprising atleast one data processor operable to process image data captured by saidcamera and to process sensor data captured by said non-imaging sensor;wherein said control, via processing at said at least one data processorof sensor data captured by said non-imaging sensor, determines presenceof an object in the field of sensing of said non-imaging sensor andahead of and being approached by the vehicle; wherein said control, viaprocessing at said at least one data processor of sensor data capturedby said non-imaging sensor as the vehicle moves along the road,determines a first distance to the detected object when said controlfirst determines presence of the object in the field of sensing of saidnon-imaging sensor based on processing at said at least one dataprocessor of sensor data captured by said non-imaging sensor; wherein,as the vehicle moves further along the road after determining the firstdistance to the detected object, said control determines presence of theobject forward of the vehicle in the field of view of said camera viaprocessing at said at least one data processor of image data captured bysaid camera; wherein said control, via processing at said at least onedata processor of sensor data captured by said non-imaging sensor as thevehicle moves further along the road, determines a second distance tothe detected object when said control first determines presence of theobject within the field of view of said camera based on processing atsaid at least one data processor of image data captured by said camera;and wherein said control determines presence of fog ahead of the vehicleresponsive to difference between the determined second distance and thedetermined first distance being at or above a threshold amount.
 11. Thefog detecting system of claim 10, wherein said non-imaging sensorcomprises a LIDAR sensor.
 12. The fog detecting system of claim 10,wherein said non-imaging sensor comprises a RADAR sensor.
 13. The fogdetecting system of claim 10, wherein said control, responsive todetermination that fog is present ahead of the vehicle, adjusts alighting system of the vehicle.
 14. The fog detecting system of claim13, wherein said control, responsive to determination that fog ispresent that is greater than a threshold degree of fog, actuates foglights of the vehicle.
 15. The fog detecting system of claim 10, whereinsaid control, responsive to determination that fog is present ahead ofthe vehicle, adjusts an adaptive cruise control system of the vehicle.16. The fog detecting system of claim 10, wherein said control,responsive to determination that fog is present ahead of the vehicle,generates an alert to a driver of the vehicle.
 17. The fog detectingsystem of claim 10, wherein said control, responsive to processing atsaid at least one data processor of image data capture by said camera,detects a headlight halo, and wherein said control, responsive toprocessing of image data captured by said camera, determines anintensity of the detected headlight halo, and wherein said control,responsive to the determined headlight halo intensity, determines a fogdensity of the determined fog.
 18. A fog detecting system for a vehicle,said fog detecting system comprising: a camera disposed at the vehicleand having a field of view forward of the vehicle, said camera capturingimage data as the vehicle travels along a road; a non-imaging sensordisposed at the vehicle and having a field of sensing forward of thevehicle, said non-imaging sensor capturing sensor data as the vehicletravels along the road; a control comprising at least one data processoroperable to process image data captured by said camera and to processsensor data captured by said non-imaging sensor; wherein said control isoperable, via processing at said at least one data processor of sensordata captured by said non-imaging sensor, to detect an object in thefield of sensing of said non-imaging sensor ahead of and beingapproached by the vehicle as the vehicle travels along the road; whereinsaid control determines a first distance to the detected object whensaid control first determines presence of the object in the field ofsensing of said non-imaging sensor based on processing at said at leastone data processor of sensor data captured by said non-imaging sensor;wherein said control, responsive to processing at said at least one dataprocessor of image data captured by said camera, determines presence ofthe object in the field of view of the camera as the vehicle travelsfurther along the road after determining the first distance to thedetected object; wherein said control determines a second distance tothe detected object when said control first determines presence of theobject within the field of view of said camera based on processing atsaid at least one data processor of image data captured by said camera;wherein said control determines that fog is present ahead of the vehicleresponsive to difference between the determined second distance and thedetermined first distance being at or above a threshold amount; andwherein, responsive to determination that fog is present ahead of thevehicle, said control at least one selected from the group consisting of(i) actuates fog lights of the vehicle and (ii) adjusts an adaptivecruise control system of the vehicle.
 19. The fog detecting system ofclaim 18, wherein said non-imaging sensor comprises a RADAR sensor. 20.The fog detecting system of claim 18, wherein said control, responsiveto processing at said at least one data processor of image data captureby said camera, detects a headlight halo, and wherein said control,responsive to processing of image data captured by said camera,determines an intensity of the detected headlight halo, and wherein saidcontrol, responsive to the determined headlight halo intensity,determines a fog density of the determined fog.